1. Field of the Invention
The present invention relates to a combination type thin film magnetic head having an inductive type thin film magnetic head element serving as a writing magnetic converting element and a magnetoresistive type thin film magnetic head element serving as a reading magnetic converting element stacked one on the other, and a method of manufacturing the same. More particularly, the present invention relates to an inductive type writing thin film magnetic head having a narrow record track for attaining a high surface recording density on a magnetic record medium by utilizing magnetic materials having a high saturation magnetic flux density, and a method of manufacturing the same.
2. Description of the Related Art
Recently a surface recording density of a hard disc device has been improved, and it has been required to develop a thin film magnetic head having an improved performance accordingly. A recent magnetoresistive type thin film magnetic head using a GMR (Giant Magneto-Resistive) element has a surface recording density up to 100 gigabits/inch2. A combination type thin film magnetic head is constructed by stacking an inductive type thin film magnetic head intended for writing information on a magnetic record medium and a magnetoresistive type thin film magnetic head intended for reading information out of the magnetic record medium on a substrate. As a reading magnetoresistive element, a GMR element having a magnetoresistive change larger than a normal anisotropic MR element by 5-15 times has been used. In order to improve a performance of the GMR element, there have been various proposals.
In a normal anisotropic MR element, a single film of a magnetic material showing the magnetoresistive effect is utilized. Many GMR elements have a multi-layer structure having a stack of a plurality of films. There are several mechanisms for generating a resistance change in the GMR element, and the multi-layer structure is dependent upon a mechanism. For instance, a super-lattice GMR film and a glanular film have a simple structure and a large resistance change under a weak magnetic field. A spin-valve GMR film will be suitable for a large scale manufacture.
As stated above, a desired high surface recording density can be simply attained by changing the AMR element by the GMR element as long as the reproducing thin film magnetic head is concerned, and a surface recording density could be further increased by utilizing a magnetic material having a higher magnetoresistive sensitivity. A performance of a reproducing head element is also dependent upon a pattern width in addition to the above mentioned selection of material. The pattern width includes a MR height and track width. A track width is determined by a photolithography process and a MR height is determined by an amount of polishing for forming an air bearing surface (ABS).
At the same time, the performance of the recording magnetic head is also required to be improved in accordance with the improvement of the performance of the reproducing magnetic head. In order to increase a surface recording density, it is necessary to realize a high track density on a magnetic record medium. To this end, a pole portion of the recording thin film magnetic head element has to be narrowed in a sub-micron order by utilizing the semiconductor manufacturing process. However, upon decreasing a track width by utilizing the semiconductor manufacturing process, there is a problem that a sufficiently large magnetic flux could not be obtained due to a miniaturized structure of the pole portion. In order to solve such a problem, there has been proposed to make at least a pole portion of a recording head element of a magnetic material having a high saturation flux density (Hi-Bs material).
FIGS. 1-5 show successive steps of a method of manufacturing a conventional combination type thin film magnetic head. In these drawings, A represents a cross sectional view cut along a plane perpendicular to the air bearing surface ABS and B denotes a cross sectional view of a pole portion cut along a plane parallel to the air bearing surface ABS. FIG. 6 is a plan view showing schematically the structure of the known combination type thin film magnetic head.
As shown in FIG. 1, an alumina (Al2O3) insulating film 12 having a thickness of about 2-3 xcexcm is deposited on a substance 11 made of AlTiC. Next, a bottom shield film 13 made of a magnetic material for magnetically shielding a GMR reading head element from an external magnetic field. On the bottom shield film 13, a shield gap film 14 made of alumina is formed with a thickness of 300-350 xc3x85 by sputtering. Then, a GMR film 15 having a given layer-structure is formed, and lead electrodes 16 for the GMR film are formed by a lift-off process. Next, a top shield gap film 17 made of alumina is formed with a thickness of 300-350 xc3x85 by sputtering, and a magnetic film 18 serving as a top shield film is formed with a thickness of about 3 xcexcm.
Next, an isolation film 19 made of alumina is formed with a thickness of about 0.3 xcexcm for isolating the reading GMR head element from a writing induction type thin film magnetic head element to suppress noise in a reproduced output from the GMR head element. After that, a bottom pole 20 of the recording head element made of permalloy is formed with a thickness of 1.5-2.0 xcexcm as illustrated in FIG. 1. It should be noted that in the drawings a ratio of thickness of various portions does not exactly correspond to an actual ratio. For instance, the isolation film 19 is shown to have a smaller thickness.
Next, as depicted in FIG. 2, on the bottom pole 20, is formed a write gap film 21 having a thickness of about 2000 xc3x85, and a top pole 22 made of permalloy which is a magnetic material having a high saturation magnetic flux density is formed in accordance with a given pattern. At the same time, a bridge film 23 for magnetically coupling the bottom pole 20 with the top pole 22 at a back-gap is formed. The top pole 22 and bridge film 23 are formed by plating with a thickness of about 3-4 xcexcm.
Then, in order to avoid a widening of an effective track width, i.e. in order to prevent a magnetic flux from extending at the bottom pole 20 during a writing operation, the write gap film 21 and the underlying bottom pole 20 around the top pole 22 are etched by ion milling to form a so-called trim structure. After that, forming an alumina insulating film 24 having a thickness of about 3 xcexcm over a whole surface, a surface is flattened by the chemical mechanical polishing (CMP) as shown in FIG. 3.
Next, as illustrated in FIG. 4, a thin film coil 25 is formed on the flattened surface by the electrolytic plating of Cu in accordance with a given pattern, and an insulating film 26 which supports the thin film coil 25 in an electrically insolated manner is formed by photoresist. Next, as depicted in FIG. 5, a top pole 28 made of permalloy is formed with a thickness of about 3 xcexcm such that the top pole 22 and bridge film 23 are coupled with each other by the top pole 28. Next, a whole surface is covered with an overcoat film 29 made of alumina. It should be noted that during the formation of the top pole 28, an electrically conductive film 29 for connecting the thin film coil 25 to an external circuit is formed with a same magnetic material as that of the top pole 28. Finally, an end surface into which the GMR film 15, write gap film 21, top pole 22 and so on are exposed is polished to form an air bearing surface ABS to complete a slider.
FIG. 6 shows a cross sectional view and a plan view illustrating the structure of the known combination type thin film magnetic head manufactured in the manner explained above. The bottom pole 20 has a large area, but the top poles 22 and 28 have a smaller area than the bottom pole. One of factors determining the performance of the writing head element is a throat height TH. The throat height TH is a distance from the air bearing surface ABS to an edge of the insulating film 26 which isolates the thin film coil 25 in an electrically insulating manner, and this distance is desired to be short. One of factors determining the performance of the reading head element is an MR height MRH. This MR height (MRH) is a distance from the air bearing surface ABS into which one edge of the GMR film 15 is exposed to the other edge of the GMR film. During the manufacturing process, a desired MR height MRH is obtained by controlling an amount of polishing the air bearing surface ABS.
There is another factor determining the performance of the thin film magnetic head together with the above mentioned throat height TH and MR height MRH. This factor is an apex angle xcex8, which is defined by an angle formed by a tangential line to a side wall of the insulating film 26 isolating the thin film coil 25 and an upper surface of the top pole 28. In order to miniaturize the thin film magnetic head, it is required to increase the apex angle xcex8 as large as possible.
Now problems in the known combination type thin film magnetic head mentioned above will be explained. After forming the insulating film 26 such that the thin film coil 25 is supported by the insulating film in an electrically insulating manner, the top pole 28 is formed. In this case, the top pole 28 has to be formed into a given pattern along the side wall of the insulating film 26. To this end, a photoresist is formed with a thickness of 3-4 xcexcm at a step of the insulating film 26 having a height of about 7-10 xcexcm. Now it is assumed that at the side wall of the insulating film 26, the photoresist should have a thickness of at least 3 xcexcm, a thickness of the photoresist at the bottom of the step would become thick such as 8-10 xcexcm. Since a width of record track of the writing head is mainly determined by a width of the top pole 22, it is not necessary to miniaturize the top pole 28 compared with the top pole 22, but if the track width of submicron order such as 0.2 xcexcm is desired, the pole portion of the top pole 28 should be miniaturized in the order of submicrons.
Upon forming the top pole 28 into a desired pattern by plating, the photoresist has to be deposited on the top pole 22 and insulating film 26 having the step of more than 10 xcexcm such that the photoresist has a uniform thickness. Then, the photoresist is subjected to the exposure of light to form the top pole 28 having the pole portion of submicron order. That is to say, a pattern of submicron order should be formed with the photoresist having a thickness of 8-10 xcexcm. When the pole portion 28 is formed by plating, a seed layer made of permalloy serving as an electrode is previously formed. During the light exposure of the photolithography, light is reflected by the permalloy seed layer, and a desired pattern might be deformed. Therefore, it is quite difficult to form the pattern of submicron order precisely.
In order to improve the surface recording density, it is required to miniaturize the pole portion as explained above. Then, the miniaturized pole portion must be made of a magnetic material having a high saturation magnetic flux density. IN general, FeN and FeCo have been known as magnetic materials having a high saturation magnetic flux density. However, these magnetic materials could not be easily formed by sputtering into a film having a given pattern. It has been known to shape the sputtered film into a given patter by the ion milling. However, etching rate is too slow and a track width of submicron order could not be controlled precisely.
NiFe, CoNiFe, FeCo have been known to have a high saturation magnetic flux density, and these magnetic materials could be formed into a given pattern by plating. For instance, Fe rich NiFe (more than 50%) has a saturation magnetic flux density of 1.5-1.6 tesla (T), and a composition could be controlled stably. However, in order to realize a surface recording density of 80-100 gigabits/inch2, a track width has to be not larger than 0.2 xcexcm. Then, there would be required to use a magnetic material having a higher saturation magnetic flux density. There has been proposed to form a magnetic film by plating using CoNiFe. However, this magnetic material could provide the magnetic faculty of about 1.8-2.0 T. In order to realize the surface recording density of about 80-100 gigabits/inch2, it is desired to use a magnetic material having a high saturation magnetic flux density such as 2 T.
A high frequency performance of the induction type thin film magnetic head is also determined by a magnetic path length which is defined as a length from the throat height zero position to the back-gap. A high frequency performance of the thin film magnetic head is improved by shortening the above mentioned magnetic path length. It would be possible to shorten the magnetic path length by reducing a pitch of successive coil windings of the thin film coil 11, but this solution has a limitation. Then, there has been proposed to construct the thin film coil to have two coil layers. Upon forming the two-layer thin film coil, after forming a first thin film coil layer, an insulating film of photoresist is formed with a thickness of about 2 xcexcm. This insulating layer has a round outer surface, and thus upon forming a second thin film coil layer, a seed layer for electrolytic plating has to be formed on an inclined portion. Therefore, upon etching the seed layer by the ion milling, a portion of the seed layer hidden by the inclined portion could not be removed sufficiently and coil windings might be short-circuited. Therefore, the second thin film coil has to be formed on a flat surface of the insulating layer.
For instance, it is now assumed that a thickness of the first thin film coil layer is 2-3 xcexcm, a thickness of the insulating film formed on the first thin film coil layer is 2 xcexcm, and an apex angle of the inclined portion of the insulating film is 45-55xc2x0, an outer surface of the second thin film coil layer must be separated from the throat height zero reference position by a distance of 6-8 xcexcm which is twice of a distance from the throat height zero reference position to the outer surface of the first thin film coil layer. Then, a magnetic path length would be longer accordingly. When the thin film coil has space/line of 1.5 xcexcm/05 xcexcm and a total number of coil windings is eleven, six coil windings are provided in the first thin film coil layer and five coil windings are formed in the second thin film coil layer. Then, a length of the whole thin film coil becomes 11.5 xcexcm. In this manner, in the known thin film magnetic head, a magnetic path length could not be shortened, and a high frequency property could not be improved.
The present invention has for its object to provide a thin film magnetic head, in which the above mentioned various problems of the conventional combination type thin film magnetic head can be solved or mitigated, while a miniaturized pole portion of submicron order could be realized and the surface recording density can be improved with preventing the undesired side writing.
It is further object of the invention to provide a combination type thin film magnetic head having a shortened magnetic path length to improve a high frequency property.
It is another object of the invention to provide a method of manufacturing precisely a combination type thin film magnetic head having a miniaturize pole portion of submicron order.
It is still another object of the invention to provide a method of manufacturing a combination type thin film magnetic head with an improved high frequency property by shortening a magnetic path length.
According to the invention, a combination type thin film magnetic head comprises a substrate, an inductive type thin film magnetic head element and a magnetoresistive type thin film magnetic head element which are formed one on the other such that these magnetic head elements are supported by the substrate and air bearing surface is defined; wherein said inductive type thin film magnetic head element includes;
a first pole made of a magnetic material which extends inwardly from said air bearing surface;
a write gap film made of a non-magnetic material and formed on one surface of said first pole to extend inwardly from said air bearing surface over at least a distance of a pole chip;
a bottom track pole made of a magnetic material and formed on a surface of said write gap film opposite to a surface which is brought into contact with said first pole to extend inwardly from said air bearing surface over at longest said distance of the pole chip;
a first non-magnetic material film formed to extend inwardly over a given distance such that the first magnetic material film includes an outer end wall which defines a throat height zero reference position together with an inner end surface of the bottom track pole opposite to the air bearing surface and the first magnetic material film has a flat surface which is coplanar with a second surface of the bottom track pole opposite to a first surface which is brought into contact with said write gap film;
an top track pole formed on said flat coplanar surface of the bottom track pole and first non-magnetic material film to extend inwardly from said air bearing surface to at least the inner end surface of the first non-magnetic material film such that said top track pole includes a track chip portion which exposes to the air bearing surface and a contact portion having a width larger than the track chip portion;
a second non-magnetic material film formed such that aligned side walls of the bottom track pole, first non-magnetic material film and top track pole are surrounded by said second non-magnetic material film and the second non-magnetic material film has a flat coplanar surface together with a second surface of the top track pole opposite to a first surface which is brought into contact with the flat coplanar surface of the bottom track pole and first non-magnetic material film;
a thin film coil formed in an electrically isolated manner inwardly with respect to an end surface of the second non-magnetic material film which is brought into contact with the aligned end surfaces of the first non-magnetic material film and the contact portion of the top track pole; and
a second pole made of a magnetic material such that the second pole has one end which is magnetically coupled with the contact portion of the top pole and the other end which is magnetically coupled with the first pole at a back-gap remote from the air bearing surface, said second pole surrounding a part of the thin film coil together with first pole.
In the combination type thin film magnetic head according to the invention, it is preferable that said bottom track pole and top track pole are formed by RIE (Reactive Ion Etching) in a self-aligned manner and a surface of said second non-magnetic material film opposite to said flat coplanar surface together with the top track pole is extended toward said first pole beyond said write gap film to construct a trim structure. Furthermore, said thin film coil is preferably formed on the flat coplanar surface of the top track pole and second non-magnetic material film. Moreover, said top track pole may be preferably made of FeN, FeCo, CoNiFe, FeAlN or FeZrN, and said bottom track pole may be preferably made of FeN, FeCo, CoNiFe, FeAlN, FeZeN or NiFe. In this case, CoNiFe, FeCo and NiFe may be formed as a plating film, and FeN, FeCo, FeAlN and FeZrN may be formed as a sputtering film.
According to the invention, a method of manufacturing a combination type thin film magnetic head including a substrate, an inductive type thin film magnetic head element and a magnetoresistive type thin film magnetic head element which are supported by the substrate to define an air bearing surface, wherein a process of forming said inductive type thin film magnetic head element comprises:
a step of forming a first pole made of a magnetic material;
a step of forming a write gap film made of a non-magnetic material on one surface of said first pole;
a step of forming a first magnetic material film on a surface of said write gap film;
a first etching step for removing said first magnetic material film such that a portion of the first magnetic material film extending from at least a position which will define an air bearing surface to a throat height zero reference position;
a step of forming a first non-magnetic material film such that the first non-magnetic material film is brought into contact with said first magnetic material film at said throat height zero reference position;
a step of polishing said first non-magnetic material film to form a flat surface which is coplanar with a surface of said first magnetic material film opposite to a surface which is brought into contact with said write gap film;
a step of forming, on said flat coplanar surfaces of the first magnetic material film and first non-magnetic material film, an top track pole made of a magnetic material such that the top track pole includes a track chip portion which extends inwardly from at least said position for defining the air bearing surface to at least an inner end surface of said first non-magnetic material film and a contact portion which continues from said track chip portion and has a wider width than said track chip portion;
a second etching step for selectively removing said first non-magnetic material film and first magnetic material film to form a bottom track pole by a reactive ion etching, while said top track pole is used as a mask;
a step of forming a second non-magnetic material film in an area which is removed by said second etching step;
a step of polishing said second non-magnetic material film to obtain a flat surface which is coplanar with the surface of said top track pole; a step of forming a thin film coil in an inner area with respect to adjoining end surfaces of the first and second non-magnetic material films such that the thin film coil is isolated electrically; and
a step of forming a second pole made of a magnetic material such that one end of the second pole is magnetically coupled with said contact portion of the top track pole and the other end is magnetically coupled with said first pole at a back-gap remote from the air bearing surface.
In the method of manufacturing a combination type thin film magnetic head according to the invention, it is preferable that during said second etching step, after forming said bottom track pole, RIE is continued to remove selectively said write gap film and to remove said fist pole over a distance smaller than a thickness of the fist pole to form a trim structure. In this case, said step of forming the top track pole includes a step of forming a flat second magnetic material film on the flat coplanar surfaces of said first magnetic material film and first non-magnetic material film, a step of forming a mask having a given pattern corresponding to a shape of the top track pole to be formed on said second magnetic material film, and a step of selectively removing said second magnetic material film by the RIE using said mask, wherein the bottom track pole can be formed in a self-aligned manner by continuing the RIE to partially remove said first magnetic material film. Furthermore, it is preferable that said first magnetic material film is made of FeN or FeCo, said second magnetic material film is formed by plating of FeN or FeCo, and the RIE for selectively removing the first and second magnetic material films is performed at a high etching temperature above 50xc2x0 C., particularly 200-300xc2x0 C. under an atmosphere of Cl2 or a mixed gas of Cl2 and boron series gas such as BCl2 or a mixed gas of Cl2 and an inert gas such as Ar and N2.
In the method of manufacturing a combination type thin film magnetic head according to the invention, it is preferable that said step of forming the top track pole includes a step of forming a flat second magnetic material film on the flat coplanar surfaces of said first magnetic material film and first non-magnetic material film, and a step of forming the top track pole by using a mask having a given pattern corresponding to a shape of the top track pole to be formed on said second magnetic material film, wherein said first magnetic material film is removed by the RIE using said mask to form the bottom track pole in a self-aligned manner. In this case, the etching may be carried out under the same condition as that mentioned above.